Data storage devices can be incorporated into a wide range of devices, including large scale data centers, laptop or desktop computers, tablet computers, digital video recorders, set-top boxes, digital recording devices, digital media players, video gaming devices, video game consoles, cellular telephones, and the like. Data storage devices may include hard disk drives (HDD). HDDs include one or multiple magnetic disks having positive or negative areas of magnetization. A bit of data may be represented according to a defined area of magnetization, which may be referred to as a bit cell or magnetic element. Blocks of data are arranged to form tracks on a rotating disk surface. A magnetic transducer may be used to read data from the disk. Different magnetic recording techniques may be used to store data to the disk. Magnetic recording techniques include, for example, longitudinal magnetic recording (LMR), perpendicular magnetic recording (PMR), and shingled magnetic recording (SMR). Heat assisted magnetic recording (HAMR) may be used with LMR, PMR, or SMR.
To increase the areal density of a disk the size of magnetic elements may be reduced. However, smaller magnetic elements may be thermally unstable (i.e., erased due to ambient temperature fluctuations). In order to have smaller magnetic elements that maintain their state at room temperature, the smaller magnetic elements can be composed of high coercivity material. However, it may be difficult to write data to high coercive materials at room temperature using the magnetic field produced by a recording head. HAMR is a magnetic recording technique that allows data to be written to a magnetic disk composed of small high coercive magnetic elements by increasing the temperature of a magnetic element on the disk as the bits of data are written. Thus, HAMR may allow for higher areal densities than conventional LMR, PMR and SMR. HAMR may also be referred to as thermally assisted (magnetic) recording (TAR or TAMR), or energy assisted magnetic recording (EAMR).